D-LATCH
Transparent D latch
Follows the input data while its latch-enable condition is active and retains it when that condition ends.
Schematic
IEC · C1 1D
IEC transparent D latch (rectangular form)
IEC bistable with a static C1 control and 1D input; the output follows D while C1 is active.
In plain English
What does IEC transparent D latch (rectangular form) mean?
The transparent latch is drawn like the D flip-flop but the C1 input has no dynamic wedge. While C1 is at its internal 1 state, the output follows the 1D input; when C1 returns to 0 the last value is held. TI's overview describes this as a level-operated control input.
A simple example
Latches are used to capture data from a bus or to hold a value for a display or relay driver. In octal devices the common-control block carries C1 and the output enable, with eight per-bit elements below.
What the drawings help you do
Because the output follows the input during the active level, glitches on D during that time pass through. The symbol shows this behaviour only through the absence of the wedge, so check it carefully.
This particular reference
IEC bistable with a static C1 control and 1D input; the output follows D while C1 is active. The IEC D flip-flop has a dynamic wedge on C1 and captures only at the edge.
- Normally open / normally closed
- The contact state in the normal condition defined for the drawing.
- Coil
- A wound conductor that can produce a magnetic field when energised.
- Signal
- Electrical information passed between devices, rather than necessarily the main power supply.
Read the source: Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A) · SN74HC373 — transparent D latches
IEC · Rectangular bistable with static C1 and 1D inputs
Qualifying-symbol and dependency conventions as explained in TI's public overview of IEEE Std 91-1984, which incorporates IEC 617-12 work. Independent educational drawing; not certified IEC geometry or an IEC database identifier. The counterpart is the matching functional concept; no equivalence of every detailed standard graphic is asserted.
Shown as an independently authored educational illustration. Use the cited publication and drawing legend to verify the required drafting form.
Schematic · C1 1D
What it represents
The transparent latch is drawn like the D flip-flop but the C1 input has no dynamic wedge. While C1 is at its internal 1 state, the output follows the 1D input; when C1 returns to 0 the last value is held. TI's overview describes this as a level-operated control input.
Latches are used to capture data from a bus or to hold a value for a display or relay driver. In octal devices the common-control block carries C1 and the output enable, with eight per-bit elements below.
Because the output follows the input during the active level, glitches on D during that time pass through. The symbol shows this behaviour only through the absence of the wedge, so check it carefully.
How to read it
- No wedge on C1 means level-sensitive.
- In octal parts, look for C1 in the common-control block.
Information to show or reference
- Draw C1 without a dynamic mark.
- Prefix the data input with 1.
- Show output enable separately if present.
A distinction that matters
The IEC D flip-flop has a dynamic wedge on C1 and captures only at the edge.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)
Transparent latch behaviour with level-operated control input.
SN74HC373 — transparent D latches
Transparent latch documentation.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
Explore related references
Put the reference into a drawing workflow.
Elora Grid helps electrical teams work with drawings, specifications and equipment information. Explore the drafting workflow or join the early-access waitlist.